Analysis of Trace Elements in Flue Gas Desulfurization Water in the Coal Combustion System and the Removal of Boron and Mercury from the Water

A detailed analysis was performed on the slurry supernatant water obtained from a wet flue gas desulfurization (FGD) system in a pilot plant of a coal combustion facility using five different coals. The determination of trace elements in those samples was performed by use of inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), and other methods, while the analysis of major cations and anions was conducted by ICP-AES and ion chromatography, respectively. The levels of B, Se, and Hg in the FGD water were sometimes high (44-62 mg/L for B, 0.24-0.37 mg/L for Se, and 0.11-0.23 mg/L for Hg), and these values exceeded the Japanese national effluent standards for terrestrial water (10, 0.1, and 0.005 mg/L for B, Se, and Hg, respectively). Simulated FGD water was prepared as a result of the analysis mentioned above, and the removal of those hazardous elements was attempted using various adsorbents, including N-methylglucamine resins (DIAION CRB02 and CFtB05), a N-methylglucamine fiber (Chelest fiber GRY-L), an iminodiacetic acid resin (DIAION CR11), a polyamine resin (DIAION CR20), an anion-exchange resin (DOWEX 1X8), activated alumina, and activated carbon. For the simultaneous removal of B and Hg from the simulated FGD water, which contained 60 mg/L of B and 0.11 mg/L of Hg, CRB02 was the most effective and the percent removal values for B and Hg were 88 and 9796, respectively. The resulting water met the effluent standards.